package com.carefree.bookmall.common.utils;

import org.apache.commons.codec.binary.Base64;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

/**
 * @ClassName:AESEncryptUtil
 * @Description: AES加解密工具类
 * @Author Tengbin
 */
public class AesEncryptUtil {

    /**
     * key
     */
    //使用AES-128-CBC加密模式，key需要为16位,key和iv可以相同！
    private static final String KEY = "w1DejXR412FFazy9";
    private static final String IV = "eEhk6S39w877UyWB";

    private volatile static AesEncryptUtil aesEncryptUtil;

    // 单例
    private AesEncryptUtil() {
    }

    public static AesEncryptUtil getInstance() {
        // 双重检查锁
        if (aesEncryptUtil == null) {
            synchronized (AesEncryptUtil.class) {
                if (aesEncryptUtil == null) {
                    aesEncryptUtil = new AesEncryptUtil();
                }
            }
        }
        return aesEncryptUtil;
    }


    /**
     * 加密方法
     * * @param data  要加密的数据
     * * @param key 加密key
     * * @param iv 加密iv
     * * @return 加密的结果
     * * @throws Exception
     */
    private String encrypt(String data, String key, String iv) throws Exception {
        try {
            //"算法/模式/补码方式"
            Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
            int blockSize = cipher.getBlockSize();

            byte[] dataBytes = data.getBytes();

            int plaintextLength = dataBytes.length;

            if (plaintextLength % blockSize != 0) {
                plaintextLength = plaintextLength + (blockSize - (plaintextLength % blockSize));
            }
            byte[] plaintext = new byte[plaintextLength];

            System.arraycopy(dataBytes, 0, plaintext, 0, dataBytes.length);

            SecretKeySpec keyspec = new SecretKeySpec(key.getBytes(), "AES");

            IvParameterSpec ivspec = new IvParameterSpec(iv.getBytes());

            cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);

            byte[] encrypted = cipher.doFinal(plaintext);

            return new Base64().encodeToString(encrypted);

        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 解密方法
     *
     * @param data 要解密的数据
     * @param key  解密key
     * @param iv   解密iv
     * @return 解密的结果
     * @throws Exception
     */
    private String desEncrypt(String data, String key, String iv) throws Exception {
        try {
            byte[] decode = new Base64().decode(data);

            Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");

            SecretKeySpec keyspec = new SecretKeySpec(key.getBytes(), "AES");

            IvParameterSpec ivspec = new IvParameterSpec(iv.getBytes());

            cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);

            byte[] original = cipher.doFinal(decode);

            String originalString = new String(original);

            return originalString;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 使用默认的key和iv加密
     *
     * @param data
     * @return
     * @throws Exception
     */
    public String encrypt(String data) throws Exception {
        return encrypt(data, KEY, IV);
    }

    /**
     * 使用默认的key和iv解密
     *
     * @param data
     * @return
     * @throws Exception
     */
    public String desEncrypt(String data) throws Exception {
        return desEncrypt(data, KEY, IV);
    }


}
